Here is a 1911 done in Slick Shot that I found. The guy that had it done said that he has firearms done in NP3 as well. It's his opinion that it's little more gray and NP3 is a little more silver. However, he feels that they are both similar in durability and lubricity.
Good info, I hadn't seen Nutmeg before. I sent an email out to them to see what their capabilities are. The Slick Shot seemed promising for a NP3 substitute.